void setup() {
  
  Serial.begin(9600);
  pinMode(2,INPUT);
  pinMode(3,OUTPUT);

}

void loop() {
  // start a measurement

  digitalWrite(3,HIGH);
  delay(10);
  digitalWrite(3,LOW);

  int duration = pulseIn(2,HIGH);

  Serial.print("Distance in cm: ");
  Serial.println(duration / 29 / 2);

  delay(1000);

}